You squirt it on your hands as you catch the office elevator for lunch, and then again on your way home. You have bottles in your bathroom and kitchen, too -- and you use them often.

You think (hope?) that your hand-sanitizer habit is protecting you from colds and flu and gross bugaboos like E. coli. But even if it isn't, it's harmless. Right?

The rumor: Hand sanitizer is not only ineffective, it's toxic

Word on the street has it that despite how clean your hands feel after using a hand sanitizer, they're actually still dirty -- and using sanitizers might actually lower your resistance to disease. Is it true?!

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When it comes to safety and effectiveness, the main concern with hand sanitizers is triclosan, which is the main antibacterial ingredient in nonalcoholic hand sanitizers.

"There's no good evidence that triclosan-containing products have a benefit," says Allison Aiello, associate professor of epidemiology at the University of Michigan. In Europe and the United States, hospitals won't even use them, she notes; it's thought that they don't reduce infections or illness.

Dr. Anna Bowen, a medical epidemiologist at The Centers for Disease Control and Prevention, says, "Triclosan-containing products don't provide any disease protection beyond what you get from washing with soap and water."

Research has shown that triclosan can disrupt the endocrine system, amplifying testosterone. In animal studies, it reduced muscle strength. It may also harm the immune system. Whether these findings add up to human toxicity isn't established yet, but the FDA is currently reviewing the issue.

A more established concern: "When you expose bacteria to triclosan, it can elicit antibiotic resistance," says Aiello. "Once the resistance is transferred, [pathogenic] bacteria can become resistant to many types of antibiotics." (Quaternary ammonium, another antibacterial found in nonalcoholic hand sanitizers, has also been shown to elicit antibiotic resistance, she says.)

The main concern with triclosan, however, is that it doesn't protect against viruses or fungi.

"Colds are caused by viruses, not bacteria," Aiello points out.

Bottom line? Skip it.

Alcohol-based sanitizers, on the other hand, are fairly effective and safe. "Hand sanitizers that are 60% alcohol are good at killing bacterial pathogens," says Bowen.

They can also kill some viruses, but not all of them -- such as the noroviruses that can cause cruise-ship outbreaks.

"They're not a panacea, but if you can't wash your hands, a squirt of an alcohol-based hand gel is a good idea," she says.

Adds Aiello, "If you can't get to a sink quickly, an alcohol-based sanitizer is a good alternative [to washing with soap and water]."

One caveat: They don't work on visibly dirty hands -- the alcohol can't get past the dirt.

And that brings us back to soap and water -- which is both safe and effective. Try to suds up after you use the toilet and before you prepare food; studies show that doing so can drastically reduce the risk of diarrhea.

"You need to wash for about 24 seconds to remove the bacteria and viruses from your hands," says Aiello. "Most people don't wash their hands properly. You need to cover all parts of your hands, including under your nails -- and then dry your hands well."

How long is 24 seconds? About as long as it takes to sing the "Happy Birthday" song two times through. So feel free to do that as you suds up.